Gas turbine engine sheet metal vane

ABSTRACT

A gas turbine engine stator vane has a sheet metal body with a pressure surface and a suction surface extending chordwise from a leading edge to a trailing edge. The sheet metal body has opposed pressure and suction side trailing end portions that meet at a joint upstream from the trailing edge of the airfoil. The pressure and suction surfaces of the sheet metal body are parallel to one another between the joint and the trailing edge, thereby forming a straight non-tapering trailing edge section from the joint to the trailing edge of the airfoil.

TECHNICAL FIELD

The application relates generally to gas turbine engines and, moreparticularly, to gas turbine engine vanes.

BACKGROUND OF THE ART

Sheet metal vanes usually have an airfoil tapering from a roundedleading edge to a sharp trailing edge. The airfoil is typically formedfrom a suction side sheet and a pressure side sheet welded together atthe airfoil leading and trailing edges by butt welds. The butt weldsneed to be ground to the parent sheet material and polished to obtainsmooth airfoil leading and trailing edges. Accordingly, extramanufacturing operations must be performed in order to obtain adequateaerodynamic surface finishes. Furthermore, the grinding and polishingoperations may compromise the quality of the butt welds. Finally, thepresence of a butt weld at the trailing edge of the airfoil does notallow altering the trailing edge section of the airfoil such as toprovide for vane flow adjustment area.

SUMMARY

In one aspect, there is provided a gas turbine engine stator vanecomprising a hollow airfoil having a sheet metal body with a pressuresurface and a suction surface extending chordwise from a leading edge toa trailing edge, the sheet metal body having opposed pressure andsuction side trailing end portions that meet at a joint upstream fromthe trailing edge of the airfoil, the pressure and suction surfaces ofthe sheet metal body being substantially parallel to one another betweensaid joint and said trailing edge, thereby forming a straight,non-tapering trailing edge section from the joint to the trailing edgeof the airfoil.

In a second aspect, there is provided a gas turbine engine stator vanecomprising a pressure side sheet and a suction side sheet joinedtogether to define an airfoil having a leading edge and a trailing edge,said pressure side sheet and said suction side sheet having a trailingend joint which is spaced chordwise from the trailing edge of theairfoil, at least one of the pressure and suction side sheets extendingchordwise beyond said trailing edge joint and defining a straighttrailing edge section having parallel suction and pressure surfaces.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures, in which:

FIG. 1 is a schematic cross-sectional view of a turbofan gas turbineengine;

FIG. 2 a is a cross-sectional view of an embodiment of a stator vanesuited for use in the engine shown in FIG. 1;

FIG. 2 b is an enlarged cross-sectional view of a trailing edge sectionof the stator vane shown in FIG. 2 a;

FIG. 3 a is a cross-sectional view of another embodiment of the statorvane; and

FIG. 3 b is an enlarged cross-sectional view of a trailing edge sectionof the stator vane shown in FIG. 3 a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a turbofan gas turbine engine 10 of a type preferablyprovided for use in subsonic flight, generally comprising in serial flowcommunication a fan 12 through which ambient air is propelled, amultistage compressor 14 for pressurizing the air, a combustor 16 inwhich the compressed air is mixed with fuel and ignited for generatingan annular stream of hot combustion gases, and a turbine section 18 forextracting energy from the combustion gases.

As well know in the art, the compressor and the turbine sections 14 and18 are provided with respective arrays of stator vanes locatedimmediately upstream of an associated rotor so as to direct the gasesonto rotor blades extending from the rotor disc. FIGS. 2 a and 2 b showa cross-sectional view of one of such stator vanes. The vane 20comprises a hollow airfoil 22 having a sheet metal body or skinextending in a chordwise direction between a leading edge 24 and atrailing edge 26. The airfoil 22 may be formed from two sheet metals (apressure side sheet 28 and a suction side sheet 30) joined together toform the airfoil concave pressure and convex suction surfaces. Thepressure and suction side sheets 28 and 30 may be joined together, suchas by welding, at a leading edge location and at an intermediatelocation 32 (FIG. 2 b) spaced chordwise from the airfoil trailing edge26.

As best shown in FIG. 2 b, the trailing edge portions of the pressureand suction side sheets 28 and 30 meet at the intermediate location 32(i.e. upstream from the trailing edge 26) and extend therefrom inintimate face-to-face contact down to the airfoil trailing edge 26.Instead of joining the pressure and suction side sheets at the trailingedge by means of a butt joint, a lap joint is rather formed at theintermediate location 32 between the pressure and suctions side sheets28 and 30. The lap joint may be formed by resistance welding, includingspot welding and seam welding. The weld extends over a distance Lsufficient to ensure the integrity of the joint between the overlappingportions of the pressure and suction side sheets 28 and 30. Theoverlapping portions of the pressure and suctions side sheets 28 and 30extending beyond the weld location 32 define a double skin, weldless,non-tapering airfoil trailing edge section 34. As can be appreciatedfrom FIG. 2 b, the airfoil pressure and suction side surfaces areparallel to one another along the full extent of the airfoil trailingedge section 34, thereby providing for a straight airfoil trailing edgeprofile with a constant wall thickness.

Such a straight airfoil trailing edge profile compared to typicaltapered trailing edge profiles may provide less aero losses at theairfoil trailing edge location where the pressure and suction flows havethe same vector. Also the straight trailing edge profile providesflexibility to make adjustment of the vane flow area. Indeed, if needbe, the airfoil trailing edge section 34 can be cutback, machined ortweak downstream of the joint 32 to provide vane flow adjustment.Trailing edge cutback is obviously not possible for conventional sheetmetal vanes having butt joints at the trailing edge.

The provision of the weld at the intermediate location 32 between theopposed inner facing surfaces of the pressure and suction side sheets 28and 30 provides for a “clean” and smooth trailing edge without requiringgrinding and polishing manufacturing steps as in the case of buttjoints. The risk that the integrity of the joint be subsequently alteredby a surface treatment is avoided.

As shown in FIGS. 3 a and 3 b, the pressure side sheet 28′ could beshorten closed to the welded joint 32′ to provide a single skin straighttrailing edge section 34′. According to this alternative, the suctionsside sheet 30′ has greater chord dimensions than the pressure side sheet28′ and the pressure and suction side surfaces of the straight trailingedge section 34′ are both defined by the suction side sheet 30′. Thisoption, when acceptable from dynamic and stress standpoints, may resultin improve dynamics, weight savings and simplified vane adjustmentprocesses.

The above description is meant to be exemplary only, and one skilled inthe art will recognize that changes may be made to the embodimentsdescribed without departing from the scope of the invention disclosed.For example, while the airfoil has been described as being formed of twosheets, it is understood that a single bended sheet could be used toform the pressure and suction sides of the airfoil. The bend woulddefine the rounded leading edge of the airfoil and the opposed terminalends of the sheet would be joined together at a location upstream of theairfoil trailing edge. Also, it is understood that the trailing edgeportions of the sheets could be joint by various bonding or weldingprocesses not only by resistance welding. Still other modificationswhich fall within the scope of the present invention will be apparent tothose skilled in the art, in light of a review of this disclosure, andsuch modifications are intended to fall within the appended claims.

1. A gas turbine engine stator vane comprising a hollow airfoil having asheet metal body with a pressure surface and a suction surface extendingchordwise from a leading edge to a trailing edge, the sheet metal bodyhaving opposed pressure and suction side trailing end portions that meetat a joint upstream from the trailing edge of the airfoil, the pressureand suction surfaces of the sheet metal body being substantiallyparallel to one another between said joint and said trailing edge,thereby forming a straight non-tapering trailing edge section from thejoint to the trailing edge of the airfoil.
 2. The stator vane defined inclaim 1, wherein said straight trailing edge section has a constant wallthickness.
 3. The stator vane defined in claim 1, wherein said sheetmetal body comprises a pressure side sheet and a suction side sheet,said pressure side sheet and said suction side sheet being in face toface contact along the extent of the straight trailing edge section. 4.The stator vane defined in claim 1, wherein said straight trailing edgesection is formed from a single sheet.
 5. The stator vane defined inclaim 1, wherein said sheet metal body comprises a pressure side sheetand a suction side sheet, the suction side sheet having a greater chorddimension than said pressure side sheet and extending chordwise beyondthe joint, the straight trailing edge section of the airfoil beingformed by the portion of the suction side sheet extending beyond thejoint.
 6. The stator vane defined in claim 1, wherein the joint is a lapjoint.
 7. The stator vane defined in claim 6, wherein the lap jointcomprises a resistance weld.
 8. A gas turbine engine stator vanecomprising a pressure side sheet and a suction side sheet joinedtogether to define an airfoil having a leading edge and a trailing edge,said pressure side sheet and said suction side sheet having a trailingend joint which is spaced chordwise from the trailing edge of theairfoil, at least one of the pressure and suction side sheets extendingchordwise beyond said trailing edge joint and defining a straighttrailing edge section having parallel suction and pressure surfaces. 9.The gas turbine engine stator vane defined in claim 8, wherein only saidsuction side sheet extends chordwise beyond the trailing edge joint todefine said straight trailing edge section of the airfoil.
 10. The gasturbine engine stator vane defined in claim 8, wherein said straighttrailing edge section is weldless.
 11. The gas turbine engine statorvane defined in claim 8, wherein said straight trailing edge section hasa constant wall thickness in a chordwise direction.
 12. The gas turbineengine stator vane defined in claim 8, wherein the trailing end joint isa lap joint provided between opposed inner facing surfaces of thepressure and suction side sheets.
 13. The gas turbine engine stator vanedefined in claim 8, wherein said pressure side sheet and said suctionside sheet are in face-to-face contact along the extent of the straighttrailing edge section.
 14. The gas turbine engine stator vane defined inclaim 12, wherein the lap joint includes a resistance weld.